A radiation-collecting device is typically a photovoltaic module comprising at least one photovoltaic cell suitable for collecting and converting the energy from radiation into electrical energy. A radiation-emitting device is typically an OLED device comprising at least one organic light-emitting diode, or OLED, suitable for converting electrical energy into radiation.
In a known manner, the energy conversion elements of a device that collects or emits radiation, namely the photovoltaic cells in the case of a photovoltaic module or the OLED structures in the case of an OLED device, comprise a material suitable for providing the energy conversion and two electrically conductive contacts on both sides of this material. However, regardless of their manufacturing technology, such energy conversion elements are susceptible to degradation under the effect of environmental conditions, in particular under the effect of exposure to air or to moisture. By way of example, for OLED structures or organic photovoltaic cells, the front electrode and the organic material are particularly sensitive to environmental conditions. For thin-film photovoltaic cells comprising an inorganic absorber layer, the front electrode of the cell, formed based on a transparent conductive oxide (or TCO) layer or based on a transparent conductive coating (or TCC), is also very sensitive to environmental conditions.
In order to protect the energy conversion elements of a device that collects or emits radiation with respect to degradations due to exposure to air or to moisture, it is known to manufacture the device with a laminated structure, in which the energy conversion elements are encapsulated and combined with a front substrate and also optionally with a rear substrate, or substrate having a support function.
Depending on the application of the device, the front and rear substrates may especially be composed of a transparent glass or of a transparent thermoplastic polymer, for example made of polyethylene, polyester, polyamide, polyimide, polycarbonate, polyurethane, polymethyl methacrylate or a fluoropolymer. In the case of a photovoltaic cell comprising an absorber layer based on a chalcopyrite compound, in particular comprising copper, indium and selenium, known as a CIS absorber layer, optionally with the addition of gallium (GIGS absorber layer), aluminium or sulphur, a polymer lamination interlayer is positioned between the front electrode and the front substrate, in order to guarantee a good cohesion of the module during its assembly, especially by lamination. It has however been observed that, when a radiation-collecting or radiation-emitting device comprises a polymer lamination interlayer or a polymer substrate positioned against an energy conversion element that is sensitive to air and/or moisture, the device exhibits a high degree of degradation. This is because the presence of the lamination interlayer, which tends to store moisture, or of the polymer substrate, which has a high permeability, promotes the migration of contaminants such as water vapor or oxygen to the sensitive element, and therefore the impairment of the properties of this element.
It is these drawbacks that the invention intends more particularly to remedy by proposing a layered element which, when it is integrated into a device that collects or emits radiation, gives this device improved resistance, especially to air and to moisture, by providing an effective and very long-term protection of the energy conversion elements of the device that are sensitive to air and/or moisture.